LTC2966CSW#PBF

LTC2966 100V Micropower Dual Voltage Monitor FEATURES DESCRIPTION Wide Operating Range: 3.5V to 100V n Wide Monitoring Range: 1.75V to 98V n Quiescent Current: 7µA n Adjustable Threshold Range n Internal High Value Resistive Dividers n ±1.4% (Max) Threshold Accuracy Over Temperature n Polarity Selection n 100V Rated Outputs n Selectable Built-In Hysteresis n 20-Lead SW and 16-Lead 3mm × 3mm QFN Packages The LTC®2966 is a low current, high voltage dual channel voltage monitor. Internal high value resistors sense the input monitor pins providing a compact and low power solution for voltage monitoring. Each channel includes two comparator reference inputs (INH/INL) to allow configuration of a high and low threshold using an external resistive divider biased from the on-chip reference. Range selection pins are provided for each channel to set the internal resistive dividers for 5x, 10x, 20x and 40x scaling. The thresholds are scaled according to the range selection settings. Additionally, either INH or INL can be grounded to enable built-in hysteresis. Polarity selection pins allow each output to be inverted. The outputs are 100V capable and include a 500k pull-up resistor to an internal supply. n APPLICATIONS n n n n Portable Equipment Battery-Powered Equipment Telecom Systems Automotive/Industrial Electronics L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners. TYPICAL APPLICATION Dual Undervoltage Monitor RANGE VIN MONITOR RANGE SELECTION 48V 24V 5V REF VINA VINB 100k 200k 91k OUTA 5V SYS LTC2966 INLA 909k INHB OUTB 5x 3.5V to 24.5V 10x 7V to 49V 20x 14V to 98V 40x 100k 48V UNDERVOLTAGE *Requires either VINA or VINB > 3.5V 24V UNDERVOLTAGE Supply Current vs VINA(B) INLB 12 PSA RS1A RS2A PSB RS1B RS2B GND 10 8 IVA(B) (µA) THRESHOLD CONFIGURATION INHA 1.75V* to 12.25V POLARITY AND RANGE SELECTION RISING THRESHOLD FALLING THRESHOLD HYSTERESIS RANGE CHANNEL A B 40.03V 20.0V 36.4V 18.2V 3.6V 1.8V 20x 10x 6 4 RANGE = 40x OUTA(B) = LOW VINB(A) = GND IREF = 0µA 2 2966 TA01a 0 0 20 40 60 VINA (V) –45°C 25°C 90°C 125°C 80 100 2966 TA01b 2966fc For more information www.linear.com/LTC2966 1 LTC2966 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Input Voltages VINA, VINB............................................. –0.3V to 140V PSA, PSB, RS1A, RS1B, RS2A, RS2B....... –0.3V to 6V INHA, INHB, INLA, INLB........................... –0.3V to 6V Output Voltages OUTA, OUTB......................................... –0.3V to 140V Average Currents VINA, VINB.........................................................–20mA OUTA, OUTB.......................................................±5mA REF.....................................................................±5mA INHA, INHB, INLA, INLB.....................................–1mA Operating Ambient Temperature Range LTC2966C................................................. 0°C to 70°C LTC2966I..............................................–40°C to 85°C LTC2966H........................................... –40°C to 125°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec).................... 300°C PIN CONFIGURATION TOP VIEW VINA 1 OUTB VINB VINA OUTA TOP VIEW 16 15 14 13 REF 1 INHA 2 17 GND INLA 3 6 7 8 RS2A PSA PSB RS2B 18 OUTB 12 GND NC 4 11 INHB REF 5 16 GND INHA 6 15 INHB INLA 7 14 INLB RS1A 8 13 RS1B RS2A 9 12 RS2B 9 5 19 NC OUTA 3 10 INLB RS1A 4 20 VINB NC 2 RS1B UD PACKAGE 16-LEAD (3mm × 3mm) PLASTIC QFN 17 NC PSA 10 11 PSB SW PACKAGE 20-LEAD PLASTIC SO TJMAX = 150°C, θJA = 68°C/W EXPOSED PAD (PIN 17) PCB GND CONNECTION OPTIONAL TJMAX = 150°C, θJA = 35°C/W ORDER INFORMATION http://www.linear.com/product/LTC2966#orderinfo LEAD FREE FINISH TUBE TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2966CUD#PBF LTC2966CUD#TRPBF LGMG 16-Lead (3mm × 3mm) Plastic QFN 0°C to 70°C LTC2966IUD#PBF LTC2966IUD#TRPBF LGMG 16-Lead (3mm × 3mm) Plastic QFN –40°C to 85°C LTC2966HUD#PBF LTC2966HUD#TRPBF LGMG 16-Lead (3mm × 3mm) Plastic QFN –40°C to 125°C LTC2966CSW#PBF LTC2966CSW#TRPBF LTC2966SW 20-Lead Plastic Small Outline (Wide .300 Inch) 0°C to 70°C LTC2966ISW#PBF LTC2966ISW#TRPBF LTC2966SW 20-Lead Plastic Small Outline (Wide .300 Inch) –40°C to 85°C LTC2966HSW#PBF LTC2966HSW#TRPBF LTC2966SW 20-Lead Plastic Small Outline (Wide .300 Inch) –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on nonstandard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix. 2966fc 2 For more information www.linear.com/LTC2966 LTC2966 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VINA = VINB = 12V, RS1/RS2 = GND, PS = GND, INH = 1.2V, INL = GND (Notes 1, 2). SYMBOL VIN VMON IVA PARAMETER Input Supply Operating Range VIN Monitor Range VINA Input Supply Current IVB VINB Input Supply Current Undervoltage Lockout Undervoltage Lockout Hysteresis Comparator Reference Input: INHA, INHB, INLA, INLB Comparator Common Mode Voltage VCM VIN Error Voltage at 96V VERR VUVLO VIN Error Voltage at 48V VIN Error Voltage at 24V VIN Error Voltage at 12V VOS AVERR VHYS Comparator Offset Voltage Internal Resistive Divider Range Error Comparator Built-in Hysteresis VHYTH tPD Built-in Hysteresis Enable Threshold VIN to OUT Comparator Propagation Delay IIN(LKG) Input Leakage Current (INH, INL) Reference: REF Reference Output Voltage VREF Noise Reference Output Noise Control Inputs: RS1A, RS2A, RS1B, RS2B, PSA, PSB Select Input Threshold VTH Input Leakage Current ILKG Status Outputs: OUTA, OUTB Voltage Output Low VOL VOH Voltage Output High IOH IO(LKG) Output Current High Leakage Current, Output High CONDITIONS VINA or VINB (Note 3) VINA = 100V, VINB = GND, 40x VINA = GND, VINB = 100V, 40x VINB = 100V, VINA = GND, 40x VINB = GND, VINA = 100V, 40x VINB = 100V, VINA = 5V, 40x VINA or VINB Rising VINA and VINB Falling l l l l l l l IREF ≤ 100µA, VIN ≥ 3.5V 100Hz to 100kHz 7 2 0.35 UNITS V V µA nA µA nA µA V mV V mV mV mV mV mV mV mV mV mV % mV mV mV µs nA nA l 40 2.45 ±1360 ±400 ±630 ±150 ±315 ±75 ±155 ±35 ±3 ±0.4 30 –14 175 80 l l ±0.1 ±0.1 ±1 ±10 2.402 140 2.426 V µVRMS 1.4 ±100 V nA 100 400 2.75 4 –5 ±250 mV mV V V µA nA ±250 ±250 ±100 ±100 ±35 ±35 ±15 ±15 ±1.9 l l l l l l l l l l l l 14 –30 100 l 2.378 l 0.4 V = 2.4V l VIN = 1.25V, I = 10µA VIN = 3.5V, I = 500µA VIN = 3.5V, I = –1µA VIN ≥ 4.5V, I = –1µA V = GND, VIN = 3.5V V = 100V, VIN = 6V l l Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. 3 7 MAX 100 98 15 ±50 15 ±50 4 3 70 l Overdrive = 10%, OUT Falling, 10x INH = GND, INL = 1.2V V = 1.2V, I-Grade V = 1.2V, H-Grade TYP l l INH = VREF, 40x 0.35V ≤ INH ≤ 2.4V, 40x INH = VREF, 20x 0.35V ≤ INH ≤ 2.4V, 20x INH = VREF, 10x 0.35V ≤ INH ≤ 2.4V, 10x INH = VREF, 5x 0.35V ≤ INH ≤ 2.4V, 5x INH = 0.35V, 10x INH = 2.4V, Range = 5x, 10x, 20x, 40x INH = GND, INL Rising INL = GND, INH Falling MIN 3.5 1.75 3 l l l l 2 2.5 –15 22 –22 2.375 3 –7.5 Note 2: All currents into pins are positive; all voltages are referenced to GND unless otherwise noted. Note 3: Requires either VINA or VINB >3.5V. 2966fc For more information www.linear.com/LTC2966 3 LTC2966 TYPICAL PERFORMANCE CHARACTERISTICS VINB Pin Current vs VINB Supply Current vs VINA(B) 12 2.5 10 RANGE = 40x OUTA(B) = LOW VINA = 5V IREF = 0µA 2.0 1.5 VREF (V) IVB (µA) 1.0 2.396 4 RANGE = 40x OUTA(B) = LOW VINB(A) = GND IREF = 0µA 2 0 20 40 60 VINA (V) –45°C 25°C 90°C 125°C –45°C 25°C 90°C 125°C 0.5 0 100 80 20 0 60 40 VINB (V) 80 2966 G01 VREF vs Load Current 2.450 VIN = 3.5V VREF (V) VREF (V) 2.375 0 0.4 1.2 1.6 0.8 LOAD CURRENT (mA) 2.0 % Range Error vs Temperature 25°C 2.400 2.350 2.7 3.0 3.5 3.2 VINA (V) 3.7 125 PROPAGATION DELAY, tPD (µs) VOS (µV) 0 –500 –1000 –1500 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 2966 G07 4.0 –0.4 –50 –25 5x 10x 20x 40x 0 25 50 75 100 125 150 TEMPERATURE (°C) 2966 G06 VIN Falling Propagation Delay vs % Overdrive VINH(L) = 1.2V 500 0 2966 G05 Comparator VOS vs Temperature 1000 0.2 –0.2 1µA 100µA 1mA 2966 G04 1500 25 50 75 100 125 150 TEMPERATURE (°C) 0.4 2.375 –45°C 25°C 90°C 125°C 0 2966 G03 VREF vs VINA(B) 2.425 2.400 2.388 –50 –25 2966 G02 2.425 2.350 100 2.392 RANGE ERROR, AVERR (%) 2.450 2.400 Built-In Hysteresis vs Temperature VINL = 1.2V VINH = GND VIN = 12V 100 75 50 –45°C 25°C 90°C 125°C 25 0 0.1 1 10 % OVERDRIVE (%) 100 2966 G08 28 |BUILT-IN HYSTERESIS| VHYS (mV) 6 0 I = –10µA 2.408 2.404 8 IVA(B) (µA) VREF vs Temperature 2.412 VINH(L) = 1.2V 26 24 22 20 18 16 –50 0 50 100 TEMPERATURE (°C) 150 2966 G09 2966fc 4 For more information www.linear.com/LTC2966 LTC2966 TYPICAL PERFORMANCE CHARACTERISTICS Voltage Output High vs Pull-Down Current (OUTA/OUTB) 4 Voltage Output Low vs Pull-Up Current (OUTA/OUTB) 1.50 VIN = 12V Voltage Output High vs Input Voltage 3.5 VIN = 12V 1.25 3.2 1.00 2.9 I = –1µA 2 VOH (V) VOL (V) VOH (V) 3 0.75 2.3 0.50 1 0 –45°C 25°C 90°C 125°C 0 –6 –9 –3 PULL-DOWN CURRENT (µA) –45°C 25°C 90°C 125°C 0.25 –12 0 2.6 0 1 5 2 3 4 PULL-UP CURRENT (mA) 2966 G10 2.0 1.7 3 4 5 6 7 8 VIN (V) 2966 G11 2966 G12 PIN FUNCTIONS Exposed Pad (UD16 Only): Exposed pad may be left floating or connected to device ground. GND: Device Ground. INHA: Channel A High Comparator Reference Input . Voltage on this pin is multiplied by the configured range setting to set the VINA high or rising threshold. Keep within valid voltage range, VCM, or tie to GND to configure built-in hysteresis where high threshold for VINA becomes INLA + VHYS scaled according to the RS pin configuration. INHB: Channel B High Comparator Reference Input . Voltage on this pin is multiplied by the configured range setting to set the VINB high or rising threshold. Keep within valid voltage range, VCM, or tie to GND to configure built-in hysteresis where high threshold for VINB becomes INLB + VHYS scaled according to the RS pin configuration. INLA: Channel A Low Comparator Reference Input. Voltage on this pin is multiplied by the configured range setting to set the VINA low or falling threshold. Keep within valid voltage range, VCM, or tie to GND to configure built-in hysteresis where low threshold becomes INHA – VHYS scaled according to the RS pin configuration. Otherwise, INHA-INLA sets the hysteresis of the Channel A comparator. Oscillation will occur if INLA > INHA unless built-in hysteresis is enabled. INLB: Channel B Low Comparator Reference Input . Voltage on this pin is multiplied by the configured range setting to set the VINB low or falling threshold. Keep within valid voltage range, VCM, or tie to GND to configure built-in hysteresis where low threshold becomes INHB – VHYS scaled according to the RS pin configuration. Otherwise, INHB-INLB sets the hysteresis of the Channel B comparator. Oscillation will occur if INLB > INHB unless built-in hysteresis is enabled. OUTA: Channel A Comparator Output. OUTA consists of a high voltage active pull-down and a gated, resistive (500kΩ) pull-up to an internally generated supply between 3.5V and 5V depending on input supply voltage. Blocking circuitry at the pin allows the pin to be resistively pulled up to voltages as high as 100V without back conducting onto the internal supply of the part. Polarity with respect to the VINA pin is configured using the polarity select pin, PSA. OUTA pulls low when the part is in UVLO. 2966fc For more information www.linear.com/LTC2966 5 LTC2966 PIN FUNCTIONS OUTB: Channel B Comparator Output. OUTB consists of a high voltage active pull-down and a gated, resistive (500kΩ) pull-up to an internally generated supply between 3.5V and 5V depending on input supply voltage. Blocking circuitry at the pin allows the pin to be resistively pulled up to voltages as high as 100V without back conducting onto the internal supply of the part. Polarity with respect to the VINB pin is configured using the polarity select pin, PSB. OUTB pulls low when the part is in UVLO. PSA: Channel A Polarity Selection. Connect to REF or a voltage >VTH to configure comparator output to be inverting with respect to VINA. Otherwise connect pin to GND to configure comparator output to be noninverting with respect to VINA. PSB: Channel B Polarity Selection. Connect to REF or a voltage >VTH to configure comparator output to be inverting with respect to VINB. Otherwise connect pin to GND to configure comparator output to be noninverting with respect to VINB. REF: Reference Output. VREF with respect to GND. Use a maximum of 1nF to bypass unless damping resistor is used. RS1A-RS2A: Channel A Range Select Input. RS1A-RS2A select 5x, 10x, 20x or 40x range for Channel A. Connect to REF or GND to configure the pin. (See Table 1) RS1B-RS2B: Channel B Range Select Input. RS1B-RS2B select 5x, 10x, 20x or 40x range for Channel B. Connect to REF or GND to configure the pin. (See Table 1) VINA, VINB: Voltage Monitor and Supply Inputs. An internal high value resistive divider is connected to the pin. The greater of VINA and VINB is used to generate an internal voltage rail with priority given to VINA. If both VINA and VINB fall below the UVLO threshold minus hysteresis, the outputs are pulled low. If VINB < VINA < 1.2V, the logic state of the outputs cannot be guaranteed. 2966fc 6 For more information www.linear.com/LTC2966 LTC2966 BLOCK DIAGRAM REF 1X VINA VREF VINB VIN PRIORITIZER GND 70M VINT + – VHYTH INHA –+ INHB 70M + VHYS VINT VHYS 500k – +– OUTA INLA OUTB INLB VHYTH – + PSA RS1A 5x/10x/20x/40x RS2A PSB RS1B RS2B CHANNEL A CHANNEL B 2966 BD 2966fc For more information www.linear.com/LTC2966 7 LTC2966 OPERATION The LTC2966 is a micropower dual channel voltage monitor with a 100V maximum operating voltage. Each channel is comprised of an internal high value resistive divider and a comparator with a high voltage output. A reference voltage is provided to allow the thresholds of each channel to be set independently. This configuration has the advantage of being able to monitor very high voltages with very little current draw while threshold configuration is done using low value resistors at low voltages. The two channels of the LTC2966 provide independent monitoring capabilities for multiple voltages or work in conjunction to set up an undervoltage/overvoltage monitor. Integration of a resistive divider for high voltage sensing makes the LTC2966 a compact and low power solution for generating voltage status signals to a monitoring system. A built-in buffered reference gives the monitor flexibility to operate independently from a high voltage supply without the requirement of additional low voltage biasing. The reference provides an accurate voltage from which a resistive divider to ground configures the threshold voltage for the internal comparators. In addition, the REF pin can be used as a logic high voltage for the range and polarity select pins. The input voltage threshold at VIN is determined by the voltage on the INH and INL pins which are scaled by the attenuation internal resistive divider. In the LTC2966 the attenuation of the internal divider is configured using two range select pins, RS1 and RS2 to select 5x, 10x, 20x or 40x for each channel. Use Table 1 to determine the correct configuration for a desired range setting. The polarity select pins, (PSA/PSB), configure the corresponding OUT pin to be inverting or noninverting with respect to VIN allowing the part to be configured for monitoring overvoltage and undervoltage conditions with either polarity output. Table 1. VIN MONITOR RANGE RANGE SELECTION 1.75V* to 12.25V 5x 3.5V to 24.5V 10x 7V to 49V 20x 14V to 98V 40x *Requires either VINA or VINB > 3.5V. RS1 RS2 L H L H L L H H The INH pin determines the high or rising edge threshold for VIN in each channel. If the monitored voltage connected to VINA rises to the scaled INHA voltage then the OUT pin is pulled high assuming PSA is ground. Likewise, the INL pin determines the low or falling edge threshold for VIN in each channel. If VINA falls to the scaled INLA voltage then the OUT pin is pulled low assuming PSA is ground. The amount of hysteresis referred to VIN is the difference in voltage between INH and INL scaled according to the RS pin configuration. INH and INL have an allowable voltage range, VCM. Figure 1 shows the allowable monitor voltage at VIN for each range as a function of comparator reference input voltage (INL, INH). Typically, an external resistive divider biased from REF is used to generate the INH and INL pin voltages. A built-in hysteresis feature requiring only two resistors can be enabled on either the VIN rising edge by grounding INH or on the falling edge by grounding INL. For example, it is appropriate to ground INH to activate rising edge hysteresis if an accurate falling voltage threshold is required for undervoltage detection. Conversely, it is appropriate to ground INL for falling edge built-in hysteresis if an accurate overvoltage threshold is required. Do not ground both INH and INL. Oscillation occurs if VINL > VINH unless INH built-in hysteresis is enabled. 2966fc 8 For more information www.linear.com/LTC2966 LTC2966 OPERATION Supply current is drawn from the higher of VINA or VINB with priority given to VINA. If both VIN pins fall below the UVLO threshold then both OUT pins are pulled low regardless of the PS pin state. 100 40x MONITOR THRESHOLD, VIN (V) The high voltage OUT pins have the capability to be pulled up to a user defined voltage as high as 100V with an external resistor. The LTC2966 also includes an internal 500k pull-up resistor to an internal voltage between 3.5V and 5V depending on input supply voltage. (See VOH in Electrical Characteristics) Wire-OR functionality is implemented by connecting OUTA and OUTB with appropriate monitor configuration. 20x 10x 5x 10 1 0.5 1 1.5 2 2.5 COMPARATOR REFERENCE INPUT (INL, INH) (V) 2966 F01 Figure 1. Monitor Threshold Threshold vs Comparator Reference Inputs 2966fc For more information www.linear.com/LTC2966 9 LTC2966 APPLICATIONS INFORMATION Threshold Configuration The closest 1% value is 909kΩ. R2 can be determined from: Each LTC2966 channel (A/B) monitors the voltage applied to the corresponding VIN input. A comparator senses the VIN pin on one of its inputs through the internal resistive divider. The other input is connected to INH/INL that is in turn biased with external resistive dividers off of the REF pin as shown in Figure 2a and 2b. The VIN rising and falling thresholds are determined by: VIN(RISE) = RANGE • VINH Where RANGE is the configured range of the internal resistive divider. In order to set the threshold for the LTC2966, choose an appropriate range setting for the desired VIN voltage threshold such that the INH and INL voltages are within the specified common mode range, VCM. For example, if a falling threshold of 18V is desired for monitoring a 24V power supply then a range greater than 10x is allowed. However, to maximize the accuracy of the VIN threshold the smallest acceptable range is used, 10x in this case. To implement 2V of hysteresis referred to VIN this means: VINH = 2V, VINL = 1.8V With 10x range the VIN thresholds are: VIN(RISE) = 20V, VIN(FALL) = 18V One possible way to configure the thresholds is by using three resistors to set the voltages on INH and INL. See Figure 2a. The solution for R1, R2 and R3 provides three equations and three unknowns. Maximum resistor size is governed by maximum input leakage current. The maximum input leakage current below 85°C is 1nA. For a maximum error of 1% due to both input currents, the resistive divider current should be at least 100 times the sum of the leakage currents, or 0.2µA. If in this example, a leakage current error of 0.1% is desired then the total divider resistance is 1.2MΩ which results in a current of 2µA through this network. For RSUM = 1.2MΩ R SUM = R1+ R2 + R3 = ( VINH • R SUM ) – R1 VREF ( 2V • 1.2MΩ ) 2.402V – 909kΩ = 90.2kΩ The closest 1% value is 90.9kΩ. R3 can be determined from RSUM: R3 = RSUM – R1 – R2 = 1.2MΩ – 909kΩ – 90.9kΩ = 200.1kΩ VIN(FALL) = RANGE • VINL R1= R2 = The closest 1% value is 200kΩ. Plugging the standard values back into the equations yields the design values for the VINH and VINL voltages: VINH = 2.001V, VINL = 1.819V The corresponding threshold voltages are: VIN(RISE) = 20.01V, VIN(FALL) = 18.19V Another possible way to configure the thresholds is with independent dividers using two resistors per threshold to set the voltages on INH and INL. See Figure 2b. Care must be taken such that the thresholds are not set too close to each other, otherwise the mismatch of the resistors may cause the voltage at INL to be greater than the voltage at INH which may cause the comparator to oscillate. As in the previous example, if RSUM = 1.2MΩ is chosen and the target for VINL is 1.8V: R SUM = R1+ R2 R1= ( VINL • R SUM ) = ( 1.8V • 1.2MΩ ) = 899.5kΩ VREF 2.402V The closest 1% value is 909kΩ. R2 can be determined by: R2 = ( V REF – V INL ) • R1 V INL ( 909kΩ ) = ( 2.402V – 1.8V ) • = 304kΩ 1.8V ( VINL • R SUM ) = ( 1.8V • 1.2MΩ ) = 899.5kΩ VREF 2.402V 2966fc 10 For more information www.linear.com/LTC2966 LTC2966 APPLICATIONS INFORMATION The closest 1% value is 301kΩ. Plugging the standard values back into the equation for VINL yields the design voltage for VINL: (R1• VREF ) ( 909kΩ • 2.402V ) V INL = = = 1.804V R1+ R2 301kΩ + 909kΩ ( ) ( ) At this point in the independent divider example only the values required to set the voltage at INL have been found. Repeat the process for the INH input by substituting the above equations with VINH for VINL, R3 for R1, R4 for R2 and VINH = 2.0V. R3 VIN VIN VINA REF OUTA 1/2 LTC2966 RS1A VINA REF OUTA 1/2 LTC2966 RS1A INHA R1 R4 INHA RS2A R2 INLA R2 PSA GND INLA R1 R3 VIN(RISE) = RANGE • (INL + VHYS) VIN(FALL) = RANGE • INL Figure 3b introduces built-in hysteresis on the falling edge because INL is pulled to ground. Similarly, a two-resistor network, R3 and R4, is used to set the voltage on INH using: R4 V = REF – 1 R3 V INH Using built-in hysteresis the VIN thresholds are: VIN(RISE) = RANGE • INH VIN(FALL) = RANGE • (INH – VHYS) RS2A PSA GND 2966 F02ab Figure 2a. Three-Resistor Threshold Configuration Using built-in hysteresis, the VIN thresholds are: Figure 2b. Two-Resistor Threshold Configuration Consider VINH = 2V with built-in hysteresis activated on the falling edge. For 10x range, 1.1% falling hysteresis is obtained. If a larger percentage of hysteresis is desired then VINH is alternatively set to 1V and the range is selected to be 20x to obtain the same VIN threshold but with 2.2% falling hysteresis. The amount of built-in hysteresis is scaled according to Table 2. If more hysteresis is needed then it is implemented in the external resistive divider as described in the Threshold Configuration section. Using Built-In Hysteresis The LTC2966 has the capability of simplifying the threshold configuration such that only two resistors per channel are required. The device pins can be configured to select a built-in hysteresis voltage, VHYS, which can be applied to either the rising or falling threshold depending on whether the INH or INL pin is grounded. Note that the hysteresis voltage at each range setting remains at a fixed value. Figure 3 introduces examples of each configuration. For example, if INH is biased from an external divider and the INL pin is grounded, then hysteresis is enabled on the low or falling threshold. The low threshold is then –VHYS relative to the high threshold determined by INH. Figure 3a introduces built-in hysteresis on the rising edge because INH is pulled to ground. A two-resistor network, R1 and R2, is used to set the voltage on INL using: R2 R1 = V REF V INL –1 VIN VIN VINA OUTA REF 1/2 LTC2966 RS1A VINA OUTA REF 1/2 LTC2966 RS1A R2 RS2A INHA RS2A INH PSA INLA R1 R4 PSA INL R3 GND GND 2966 F03ab Figure 3a. Rising Edge Built-In Hysteresis by Grounding INH Figure 3b. Falling Edge Built-In Hysteresis by Grounding INL Table 2. Built-In Hysteresis Voltage vs Range RANGE VIN REFERRED BUILT-IN HYSTERESIS 5x 110mV 10x 220mV 20x 440mV 40x 880mV 2966fc For more information www.linear.com/LTC2966 11 LTC2966 APPLICATIONS INFORMATION Error Analysis The actual VIN falling threshold has an error tolerance of ±216mV or ±1.2%. VIN thresholds are subject to the following errors: • REF Voltage Variation (∆VREF) • Comparator Offset (VOS) • Internal Divider Range Error (AVERR) Improving Threshold Accuracy The biggest threshold error terms are: • External Resistive Divider Accuracy • External Resistive Divider Error (AXERR) The effect these errors have on the VIN threshold is expressed by: VINH(L) ⎡ ⎤ VERR = RANGE • ⎢ ± VOS ± ΔVREF • ± VINH(L) • A XERR ⎥ VREF ⎣ ⎦ ±RANGE • A VERR • VINH(L) A XERR = 2 • TOLERANCE ⎛ V INH(L) ⎞ • ⎜ 1– ⎟ ⎝ 100 V REF ⎠ External divider error is determined by the percentage tolerance values of the resistors. If 1% tolerance resistors are used in the external divider then there is a 2% worst-case voltage error associated with it. The effects of comparator offset and VREF voltage are uncorrelated with each other. Therefore, a Root-Sum-Square can be applied to the error voltage referred to VIN. Using the example from Threshold Configuration and assuming 1% resistors implement the external resistive divider, the falling VIN threshold of approximately 18V has an error tolerance of: ⎛ V ⎞ VERR(REF) = (RANGE ) ⎜ ±ΔVREF • INL ⎟ VREF ⎠ ⎝ VERR = = VERR(RS) = (RANGE ) (±A VERR ) (±VINL ) 2 2 2 2 VERR(REF) + VERR(EXT) + VERR(VOS) + VERR(RS) (±9mV ) 2 2 2 + (±9mV ) + (±30mV ) + (±72mV ) 2 The resulting VIN threshold error is reduced to ±0.44% from ±1.2% in the previous error analysis example. 2 2 2 2 VERR(REF) + VERR(EXT) + VERR(VOS) + VERR(RS) 2 + (±90mV ) + (±30mV ) + (±72mV ) 2 = ±216mV 12 VINL ⎞ ⎞ ⎟⎟ VREF ⎠ ⎠ = ±79mV = (10 ) • (±0.004 ) • (1.8V ) = ±72mV 2 ⎛ ⎛ VERR(EXT) = (RANGE ) ⎜ ±VINL • 2 • 0.001• ⎜ 1– ⎝ ⎝ = (10 ) • (±0.004 ) • (1.8V ) = ±72mV VERR(VOS) = (RANGE ) (±ΔVOS ) = (10 ) • (±3mV ) = ±30mV 2 ⎛ 1.8V ⎞ = (10 ) • ⎜ ±1.024mV • ⎟ = ±9mV ⎝ 2.048V ⎠ VERR(RS) = (RANGE ) (±A VERR ) (±VINL ) = (10 ) • (±1.8V • 0.005 ) = ±90mV (±180mV ) ⎛ V ⎞ VERR(REF) = (RANGE ) ⎜ ±ΔVREF • INL ⎟ VREF ⎠ ⎝ VERR(VOS) = (RANGE ) (±ΔVOS ) = (10 ) • (±3mV ) = ±30mV ⎛ ⎛ V ⎞⎞ VERR(EXT) = (RANGE ) ⎜ ±VINL • 2 • 0.01• ⎜ 1– INL ⎟ ⎟ ⎝ VREF ⎠ ⎠ ⎝ = Even using 1% tolerance resistors, external resistive divider accuracy still accounts for as much as ±2% threshold error while REF voltage variation accounts for ±1% threshold error. In order to minimize these threshold error terms, an external reference can be used to set the thresholds for INH/INL as shown in Figure 4. An LT6656-2.048 has an initial accuracy of 0.05% and provides bias via the 0.1% resistive divider network for INH and INL. It is biased off of the LTC2966 REF pin. The threshold error tolerance is calculated using the method described in the Typical Applications section with ∆VREF = ±1.024mV given the initial accuracy of the LT6656 2.048V output and using 0.1% tolerance resistors for the external divider. = (10 ) • (±1.8V • 0.0005 ) = ±9mV ⎛ 1.8V ⎞ = (10 ) • ⎜ ±24mV • ⎟ = ±180mV ⎝ 2.402V ⎠ VERR = • REF Voltage Variation 2966fc For more information www.linear.com/LTC2966 LTC2966 APPLICATIONS INFORMATION VIN R3 47.5k 0.1% 1µF R4 10k LT6656-2.048 OUT IN GND REF VIN LTC2966 INH R2 200k 0.1% INL R1 1.8M 0.1% GND 2966 F04 Figure 4. Reducing VIN Threshold Error Disabling a Channel Figure 5 shows the proper technique for disabling a channel. Table 4 summarizes the correct connections. Correctly disabling an unused channel prevents its comparator output from chattering and introducing unwanted noise in the system. Table 4. Disabling a Channel PIN CONNECT TO VIN GND INH REF INL GND RS1 GND or REF RS2 GND or REF PS GND or REF OUT Open OPEN VINA REF OUTA 1/2 LTC2966 INHA RS1A INLA OPEN RS2A PSA GND 2966 F05 Figure 5. Disabling a Channel Output Configuration with Polarity Selection The OUT pin may be used with a wide range of user-defined voltages up to 100V with an external resistor. Select a resistor compatible with desired output rise time and load current specifications. When the status outputs are low, power is dissipated in the pull-up resistors. An internal pull-up is present if the OUT pins are left floating or if low power consumption is required. The internal pull-up resistor does not draw current if an external resistor pulls OUT up to a voltage greater than VOH. If PS is connected to ground, the comparator output is noninverting. This means that OUT pulls low when VIN falls below the scaled INL voltage. OUT is released after VIN rises above the scaled INH voltage. Likewise, if PS is connected to REF or a voltage >VTH, the comparator output is inverting. This means that OUT pulls low when VIN rises above the scaled INH voltage and is released when VIN falls below the scaled INL voltage. If both VIN pins fall below the UVLO threshold minus hysteresis, the outputs are pulled to ground. The outputs are guaranteed to stay low for VINA ≥ VINB ≥ 1.25V regardless of the output logic configuration. It is recommended that circuit board traces associated with the OUT pin be located on a different layer than those associated with the INH/INL and REF pins where possible to avoid capacitive coupling. Hot Swap Events The LTC2966 can withstand high voltage transients up to 140V. However, when a supply voltage is abruptly connected to the input resonant ringing can occur as a result of series inductance. The peak voltage could rise to 2x the input supply, but in practice can reach 2.5x if a capacitor with a strong voltage coefficient is present. Circuit board trace inductances of as little as 10nH can produce significant ringing. Ringing beyond the absolute maximum specification can be destructive to the part and should be avoided whenever possible. One effective means to eliminate ringing seen at the VIN pins and to protect the part is to include a 1kΩ to 5kΩ resistance between the monitored voltage and the VIN pin as shown in Figure 6. This provides damping for the resonant circuit. If there is a decoupling capacitor on the VINA/VINB pins the time constant formed by the RC network should be considered. 2966fc For more information www.linear.com/LTC2966 13 LTC2966 APPLICATIONS INFORMATION VIN REF RS 1k REF LTC2966 RS VINA/VINB INH CREF LTC2966 INL LTC2966 RS INH CREF INL GND GND 2966 F07ab GND 2966 F06 7a Figure 6. Hot Swap Protection 7b High Voltage Pin Creepage/Clearance Options Appropriate spacing between component lead traces is critical to avoid flashover between conductors. There are multiple industry and safety standards that have different spacing requirements depending on factors such as operating voltage, presence of conformal coat, elevation, etc. The LTC2966 is available in a 20-lead SW package which offers pin-to-pin clearance of at least 0.76mm (0.03in) to satisfy high voltage external component lead specifications for standards such as the UL60950 and IPC2221. The package incorporates unconnected pins between all adjacent high voltage and low voltage pins to maximize PC board trace clearance. For voltages >30V the SW should be used, otherwise the smaller QFN is sufficient when clearance is not an issue. For more information, refer to the printed circuit board design standards described in IPC2221 and UL60950. Voltage Reference The REF pin is a buffered reference with a voltage of VREF referenced to GND. A bypass capacitor up to 1000pF in value can be driven by the REF pin directly. Larger capacitances require a series resistance to dampen the transient response as shown in Figure 7A. If a resistive divider is already present then the bypass capacitor can be connected to the INH or INL pin as shown in Figure 7B. Figure 7C shows the resistor value required for different capacitor values to achieve critical damping. Bypassing the reference can help prevent false tripping of the comparators by preventing glitches on the INH/INL pins. Figure 8 shows the reference load transient response. Figure 9 shows the reference line transient response. If there is a decoupling capacitor on the INH/INL pin the time constant formed by the RC network should be considered. Use a capacitor with a compatible voltage rating. RESISTANCE VALUE (kΩ) 100 10 1 0.1 0.001 0.01 0.1 CAPACITANCE VALUE (µF) 1 2966 F07c 7c Figure 7. Using Series Resistance to Dampen REF Transient Response 1nF 10nF + 4.3kΩ 0.1µF + 1.5kΩ 1µF + 600Ω 2.4V 50mV/DIV 100µA VREF LOAD CURRENT 10µA 2966 F08 100µs/DIV Figure 8. VREF Load Transient 1nF 1µF + 600Ω 2.4V 10mV/DIV 8V VREF VINA 1V/DIV 3.5V 2966 F09 10µs/DIV Figure 9. VREF Line Transient 2966fc 14 For more information www.linear.com/LTC2966 LTC2966 TYPICAL APPLICATIONS 48V UV/OV Monitor ±15V Undervoltage Monitor The circuit in Figure 10 monitors a single 48V supply and is configured for UV/OV window detection. Channel A is used to monitor undervoltage conditions where the 36V threshold is determined by 1.8V at INLA scaled by 20x. Channel B is used to monitor overvoltage conditions where the 72V threshold is determined by the same 1.8V at INHB with 40x range. UV is pulled high to indicate an undervoltage condition when the supply drops below the UV threshold. Therefore PSA is pulled to REF to obtain the correct polarity on OUTA. OV is pulled high when the supply rises above the OV threshold which means PSB is pulled to ground to obtain the appropriate output polarity. Connecting INHA and INLB to ground enables internal hysteresis for each channel in the appropriate direction and reduces the number of external components. The LTC2966 can be used to monitor a positive and a negative supply simultaneously. In the circuit shown in Figure 11, Channel B is used to monitor the –15V supply by connecting VINB’s internal resistor divider to REF and configuring to 5x range. The voltage at the VIN sensing input of the Channel B comparator is fixed at 480mV. When the –15V supply is undervoltage INHB > 480mV and OUTB is pulled low because PSB is connected to ground. As the negative supply comes into regulation the comparator monitors the INHB pin to detect when its voltage crosses 480mV corresponding to –14.3V. UVB is released indicating that there is no longer an undervoltage condition. As the negative supply drops out of regulation the comparator monitors the INLB pin to detect when its voltage crosses 480mV, corresponding to –13.6V due to the external divider 48V OV/UV MONITOR CHANNEL RISING THRESHOLD FALLING THRESHOLD HYSTERESIS RANGE A 36.6V 36.0V 0.6V 20x B 72.2V 71.2V 1.0V 40x 48V 5V VINA C1 1000pF 10V VINB R3 100k REF R2 294k INHA INLA R1 887k OUTA R4 100k UV LTC2966 5V SYS INHB INLB OUTB OV PSA RS1A RS2A PSB RS1B RS2B GND 2966 F10 Figure 10. Use Range Selection and Built-In Hysteresis to Minimize External Components 2966fc For more information www.linear.com/LTC2966 15 LTC2966 TYPICAL APPLICATIONS gain. UVB is pulled low after the comparator detects the threshold crossing to indicate an undervoltage condition. Channel A is configured to monitor for an undervoltage condition on the 15V supply by pulling UVA low when the positive supply drops below 13.6V. OV thresholds, where channel A and B are configured similarly to the 48V UV/OV monitor circuit in Figure 10. Hysteresis for each comparator is implemented by the external resistor network. High voltage OUT pins allow a pair of 4N25 opto-couplers to be used in translating the status signals for the 5V system. R5, R6, R7 and R8 set the maximum current through the optos to be approximately 4.2mA. If an exposed pad is present it should be tied to the GND pin or left open. –48V UV/OV Voltage Monitor In the circuit shown in Figure 12, the LTC2966 is configured as a –48V UV/OV monitor by referencing the GND pin to the negative supply. R1 through R4 configure the UV and ±15V UV MONITOR CHANNEL RISING THRESHOLD FALLING THRESHOLD HYSTERESIS RANGE A 14.3V 13.5V 0.8V 10x B –14.4V –13.6V –0.8V 5x 15V 5V VINA RS 600 C1 1µF 10V REF R3 162k R7 100k INHA R2 12.4k R1 226k VINB R4 182k R5 8.6k R6 1.4M INLA INHB OUTA R8 100k UVA LTC2966 5V SYS OUTB UVB INLB PSA RS1A RS2A PSB RS1B RS2B GND RTN –15V 2965 F11 Figure 11. Dual Polarity Voltage Monitoring 2966fc 16 For more information www.linear.com/LTC2966 LTC2966 PACKAGE DESCRIPTION Please refer to http://www.linear.com/product/LTC2966#packaging for the most recent package drawings. UD Package 16-Lead Plastic QFN (3mm × 3mm) (Reference LTC DWG # 05-08-1691 Rev Ø) 0.70 ±0.05 3.50 ±0.05 1.45 ±0.05 2.10 ±0.05 (4 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD PIN 1 NOTCH R = 0.20 TYP OR 0.25 × 45° CHAMFER R = 0.115 TYP 0.75 ±0.05 15 PIN 1 TOP MARK (NOTE 6) 16 0.40 ±0.10 1 1.45 ± 0.10 (4-SIDES) 2 (UD16) QFN 0904 0.200 REF 0.00 – 0.05 NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WEED-2) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 0.25 ±0.05 0.50 BSC 2966fc For more information www.linear.com/LTC2966 17 LTC2966 PACKAGE DESCRIPTION Please refer to http://www.linear.com/product/LTC2966#packaging for the most recent package drawings. SW Package 20-Lead Plastic Small Outline (Wide .300 Inch) (Reference LTC DWG # 05-08-1620) .050 BSC .045 ±.005 .030 ±.005 TYP .496 – .512 (12.598 – 13.005) NOTE 4 N 20 18 17 16 15 14 13 12 11 N .325 ±.005 .420 MIN 19 .394 – .419 (10.007 – 10.643) NOTE 3 1 2 3 N/2 N/2 RECOMMENDED SOLDER PAD LAYOUT .005 (0.127) RAD MIN .009 – .013 (0.229 – 0.330) NOTE: 1. DIMENSIONS IN .291 – .299 (7.391 – 7.595) NOTE 4 .010 – .029 × 45° (0.254 – 0.737) 1 2 3 4 5 6 7 8 .093 – .104 (2.362 – 2.642) 9 10 .037 – .045 (0.940 – 1.143) 0° – 8° TYP NOTE 3 .016 – .050 (0.406 – 1.270) .050 (1.270) BSC .014 – .019 (0.356 – 0.482) TYP .004 – .012 (0.102 – 0.305) S20 (WIDE) 0502 INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS. THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS 4. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) 2966fc 18 For more information www.linear.com/LTC2966 LTC2966 REVISION HISTORY REV DATE DESCRIPTION A 09/15 Fixed typos PAGE NUMBER B 03/16 Added ABS Max Rating for INHA, INHB, INLA and INLB pins 2 C 08/17 Corrected example error threshold calculations 12 1, 3, 10, 11, 12, 15 2966fc Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representaFor more www.linear.com/LTC2966 tion that the interconnection of itsinformation circuits as described herein will not infringe on existing patent rights. 19 LTC2966 TYPICAL APPLICATION –48V UV/OV MONITOR CHANNEL A RISING THRESHOLD –40.0V FALLING THRESHOLD –36.0V HYSTERESIS –4.0V RANGE 20x 5V R9 100k B –72.0V –56.0V –16.0V 40x OV 4.2mA AT –48V RTN R8 1k 4N25 C1 1000pF 10V R3 33.2k R2 66.5k VINA REF 4N25 VINB OUTA INHA R5 10k LTC2966 INLA 5V SYS 4.2mA AT –48V R6 1k R4 66.5k R10 100k UV INHB OUTB R7 10k INLB PSA RS1A RS2A PSB RS1B RS2B GND R1 232k 2966 F12 –48V Figure 12. 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